Recently my IDE startet to let me wait almost indefinitely when starting
up. Usually it was about 6 seconds. But now the
org.eclipse.mylyn.context.ui is busy in the spash screen for additional
*2:20* minutes.

I already exported the mylyn data to a zip file, deleted (moved) the
..metadata/.mylyn folder and tried again. No change, the startup time is
still 2:30 minutes, waiting most of the time inorg.eclipse.mylyn.context.ui.